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Ductina
''Ductina'' is a genus of extinct, small to average sized, eyeless phacopid trilobite, that lived during the Devonian.
== Description ==
The body of ''Ductina'' is small to average (up to ), 1¼ to 2 times as long as wide, blunted oval. Body without any adornment. The headshield (or cephalon) is 2 to 3 times as wide as it is long in the direction of the axis (or sagittally). The cephalic axis (or glabella) is strongly widening forward with shallow furrows, the front curving downward to end at an approximate straight angle to the plain of the axis. Another shallow furrow (the occipital furrow), with left and right a deep pit (apodemal pit), crosses to the back of the glabella to define a narrow band (or occipital ring), and just in front left and right a small lobe is defined by shallow furrows and a deep pits. The back of the cephalon is often broken, obscuring the features of the occipital ring. Eyes and eye ridges (palpebral lobes) are absent.〔Dele, D.M. Secondary Blinding among the Phacopid Trilobites and its Significans. American Midland Naturalist, 18/6. 1937〕 The natural fracture lines (sutures) of the cephalon coincide with its margin (unique with the Phacopidae), so there are no free cheeks (or librigenae). The genal angles are rounded, not truncated, no genal spine. The thorax has 10 segments, and the width of the axis is about ⅓ of the thorax. Tailpiece (or pygidium) is 20 to 35% of the length of the body. The pygidial axis (or rachis) is pointed (or acute), ending at the border.〔Struve, W. Suborder Phacopina, p. O467. ''in'' Moore, R.C. (ed.). Treatise on Invertebrate Paleontology. Part O – Arthropoda (Trilobitomorpha). 1959〕
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